[bond]

Sure it can handle millions of requests a week.

So 1week=7days=168hours=10080minutes=604800seconds

For 1 million requests/week= 1.65Req/sec

For 5 million requests/week= 8.26Req/sec

For 10 million requests/week= 16.53Req/sec

For this kind of traffic there's nothing to worry about. I'm not an expert so someone with more experience can say if this numbers are ok.

[rewind]

Just don't forget to design for peak, not average (although this isn't PHP-specific).

[bond]

Yes, you're right, peak is very important.